Fuel supply control means for combustion apparatus



R. E. FELL 51' AL Filed Oct. 25, 1943 llO-V-Z FUEL SUPPLY CONTROL MEANS FOR COMBUSTION APPARATUS March 23, 1948.

INVENTOR. JOHN W. MILLER y RAYMOND E. FELL FIG.

Patented Mar. 23, 1948 FUEL SUPPLY, CONTROL MEANS FOR COMBUSTION APPARATUS Raymond E. Fell and John W. Miller, Lansing, Mich., asslgnors to Motor Wheel Corporation,- Lansing, Mich., a corporation of Michigan Application October 25, 1943, Serial No. 507,524

This invention relates to control systems for the fuel supply elements of -fluid fuel burners.

The principal object of the invention is to provide a control system for liquid fuel burners which will prevent the burner from becoming pooled, or in other words, preventing the supply of fuel to the burner at a rate greater than it can be consumed.

Another object of the invention is to provide in a burner including an electrical ignition element, means for preventing the flow of fuel to the burner when the ignition element is inoperative and the burner is not lighted.

These objects will more fully appear in the following specification when read in connection with the accompanying drawings, wherein- Figure 1 is a diagrammatic view of an oil burning furnace to which the invention is applied;

Figure 2 is a fragmentary cross-sectional view of the burner shown in Figure 1 and the controls attached thereto; and

Figure 3 is a cross-sectional view of a portion of the fuel control valve employed with the burner. 1

The invention is shown in the drawings in connection with a warm air furnace l heated by a pot type oil burner II. The burner may be of the type disclosed in the Valjean Patent No. 2,186,156, granted January 9, 1940. The burner is adapted to burn liquid fuel supplied to the bottom thereof through a pipe I2 and a shut-off control I3 from a suitable source, not shown. The rate of delivery of fuel may be regulated by any suitable means, such as the manual control I2a.

Fuel from the '-source thereof passes through the electrically operated fuel shut-off control 13 and thence through pipe I2 to the burner. The control I3 comprises a housing l4 having a valve seat I5 in the bottom thereof and an outlet passageway lfi'which is connected to pipe l2. Located within the housing I4 is a vertically reciprocable valve H. The valve is provided with a slotted lower end which is movable within the valve seat I5 to open and close the fuel passageway I8. Valve IT is surrounded by a coiled spring I8 which seats at one end against a shoulder I9 on the valve and at the other end against a collar 20 rigidly attached to the housing. The spring I8 tends to raise valve I! from its seat and permit oil to flow through the passageway IE to the burner. Maximum opening of the valve is determined by screw 2| threaded into the top of the housing. v

A heat motor 22 is provided to close the valve against the action of the spring' I8. The heat 2 Claims. (01. 158-28) Q switch 28. A suitable room temperature thermo- Figure 1.

. 2 motor 22 is a bimetallic metal strip attached at its outer end to a ledge 23 on the housing l4. The inner end of the heat motor rests upon the shoulder I9 on the valve. arranged so that when heated it tends to rise and assume the dotted line position shown in Figure 3. When the heat motor 22 is cold it forces the valve I! to closed position.

A heating coil 24 of resistance wire is wound around the motor 22 to furnish the heat to operate the same.

Mounted within the burner adjacent the fuel inlet and the bottom wall of the burner is an electrical ignition element 25. This ignition element may be of any suitable type, but preferably is similar to oneof those disclosed in our copending application Serial No. 498,320, filed August 12, 1943. When energized-the ignition element heats the bottom of the burner and any fuel thereon to the point of ignition and causes the same to ignite.

Mounted upon the burner bottom wall, preferably directly beneath the ignition element 25 is a heat responsive switch 21. The switch 21 is in heat exchange relation with the burner bottom wall. It is adapted to close when the temperature of the burner bottom rises sufiiciently and opens when the burner temperature drops below a predetermined point.

Another heat responsive switch 28, is mounted upon the side wall of the burner in heat exchange relation therewith. This switch is adapted to close when the burner is cold and open when the burner exceeds a predetermined temperature.

The wiring of the various parts is disclosed in The necessary current for energizing the heating coil 24 of the motor 22 and the ignition element 25 is supplied from the secondary 29 of a stepdown transformer. The primary 3!] of the transformer is connected to the usual household electrical supply line a The ignition element 25 is connected in series with switch'28 and the secondary 29 of the transformer. Switch 21 is connected in serieswith heating coil 24 and these two elements are connected in parallel with ignition element 25 and stat 3| is located somewhere in the space to be heated and is connected in series with the circuits of both of the switches 21 and 28 and heating coil 24 and ignition element 25. v

When the room temperature is above that for which thermostat Si is set, the thermostat 3| is open and all of the other control elements are inoperative. Assuming that the burner is cold, switch 28 will be closed and switch 21 will be open.

The heat motor is' same change relation therewith.

Switch 21 is set so that it closes when the bottom wall of the burner reaches a temperature high enough to vaporize any fuel entering the burner. As soon as the burner bottom attains that predetermined temperature switch 21 closes and heating coil 24 is energized. Coil 24 heats the motor 22 so that it bends upwardly to the dotted line position and permits valve II to open. Fuel will then flow through the passageway l8 to the burner where it is heated by the hot bottom wall of the burner and the hot ignition element 25, The fuel vapors are soon ignited and the burner operates normally.

As soon as the burner has operated in its normal manner for a short length of time the side wall of the burner becomes hot enough to affect switch 28. Switch 28 then opens, breaking the circuit of the ignition element 25. The circuit of the ignition element is not again closed until the burner cools below the temperature for which the switch 2845 set.

If for some reason the flow of fuel to the burner is greater than can be vaporized and consumed. the liquid fuel will form a pool on the bottom of the burner. This acts as an insulating blanket preventing the radiation of heat to the burner bottom and the latter begins to cool. the bottom of the burner reaches a predetermined low temperature,-switch 21 opens, de-energizing heating coil 24, and the motor 22 then closes the valve l1 shutting off the fuel. The burner will continue to operate until the fuel in the burner is consumed sufllciently to permit heat to reach the bottom' wall of the burner and rise in temperature again. Switch 21 again closes and more fuel will be admitted. This cycle will continue intermittently until the fuel flow is reduced in some manner or the cause of poor combustion of the fuel is eliminated.

Once the room in which the thermostat II is located reaches the desired temperature, thermostat 3| opens and breaks the circuit of the heat motor 22. Heat motor 22 cools and closes valve l1. What fuel remains in the burner is quickly consumed, thefire goes out, and the burner cools down. Switch 28 then closes and the burner control system is'ready for the next time when thermostat 3| calls for heat. when that occurs the cycle is repeated.

From the foregoing it will be apparent that the invention provides safety features which are not found in previous heating systems. It does not permit the flow of fuel to the burner until the burner is hot enough to receive it and promptly vaporize the fuel that enters. Furthermore, it positively prevents flooding. of the burner due to an abnormal decrease in draft or other cause.

As soon as 4 with consequent reduction in fuel consumption. This eliminates possible damage to the apparatus itself or to the building in which the. heater is located.

The scope of the invention is indicated in the appended claims.

We claim:

1. Fuel supply control means for combustion apparatus including a pot-type liquid fuel burner having a bottom wall adapted to serve as a fuel receptacle, comprising in combination, an electrical fuel ignition unit is said burner, said unit comprising an electrical heating element in heat exchange relation with the bottom wall of the burner, means including an adjustable fuel metering device for supplying 'liquid fuel to the burner, a motor associated with said metering device adapted to move the latter from opened to fully'closed position, a circuit for said motor including a thermostatic switch mounted exteriorly of the burner bottom wall adjacent said heating element and in heat exchange relation with said burner bottom wall, said switch being adapted to open or close said motorcircuit when the temperature of the burner bottom wall adjacent the switch falls below or exceeds, respectively, a. predetermined temperature.

2. Fuel supply and ignition control means for combustion apparatus including a vaporizing pot type burner having a bottom wall adapted'to serve as a fuel receptacle, comprising in combination, an electrical fuel ignition unit in the burner, said unit including an electrical heating element positioned within the burner in heat exchange relation with the bottom wall thereof, a circuit for said heating element including a switch, means including an adjustable fuel-metering device for supplying liquid fuel to the burner, a

motor associated with said metering device'for moving the latter between opened and fully closed positions, a circuit for said motor including a thermostatic switch positioned exteriorly of the burner adjacent the heating element and inheat exchange relation with said burner bottom wall,

' said last named switch beingresponsive to a predetermined rise in the temperature of the burner to close said motor circuit and to open said circuit upon a predetermined drop in the temperature of the burner bottom wall.

RAYMOND E. FELL.

JOHN W. MEIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

